DIELECTRIC-SPECTROSCOPY IN THE CULTIVATION OF SUSPENDED AND IMMOBILIZED HYBRIDOMA CELLS

Dielectric spectroscopy, also referred to as capacitance measurement, was evaluated as a tool for on-line and real-time monitoring of hybrid oma cell growth in suspension batch culture and in immobilized cell cu lture in porous glass carriers. The capacitance signal proved to be a lumped parameter influenced by cell concentration, cell size and cultu re conditions. During a batch culture the cell specific capacitance si gnal changes by about 45% having a maximum value at the maximum growth rate. An excellent correlation between the specific capacitance and t he specific amount of nucleotidetriphosphates in the cells could be sh own. Dielectric spectroscopy proved to be a useful tool for on-line mo nitoring of cell attachment and growth in open porous microcarriers in fluidized bed fermenters. Also, in this system only an approximate co rrelation with viable cell concentration appeared, whereas an exact co rrelation with the glutamine consumption rate, a measure of the metabo lic activity of the cells, could be shown. This allowed a closed loop control of the medium feed rate, which was directly linked to the capa citance signal during the entire course of a continuous fermentation. (C) 1998 Elsevier Science B.V. All rights reserved.